I'm a Diving School Dropout (due to the weight of the tanks) and a lazy day snorkeler (float on a raft with my face in a mask over the side).  If you are attempting to snorkel for the first time, read some articles about it, take lessons, practice in a pool. The proper snorkel and mask can make all the difference in the world ... and don't try to walk forward into the water with your fins ... walk backward or wait to put them on in shallow water.  Any other tips?